Answer:
Option C = 1.72 mol
Explanation:
Given data:
Mass of KF = 100 g
Moles of KF = ?
Solution:
First of all we have to calculate the molar mass of KF.
Molar mass of KF = 39.0983 g/mol + 18.998403 g/mol
Molar mass of KF = 58. 0967 g/mol
Formula:
Number of moles = mass/molar mass
Number of moles = 100 g/ 58.0967 g/mol
Number of moles = 1.72 mol
1.267 x 10 ^ 24 is the total number of atoms
We know the formula of the density:
ρ =
;
So the mass will be equal to:
m = ρ * V = 2.70 * 21.3 = 57,51 g =
57510 mg of substance.
So the answer is 57510.
Answer:
A machine have 75% efficiency means 25% of efficiency has been lost due to friction and a machine can work 75% only.